spring data jpa 组合条件查询封装

/**
 * 定义一个查询条件容器
 * @author lee
 *
 * @param <T>
 */
public class Criteria<T> implements Specification<T>{
    private List<Criterion> criterions = new ArrayList<Criterion>();  
 
    public Predicate toPredicate(Root<T> root, CriteriaQuery<?> query,
            CriteriaBuilder builder) {
        if (!criterions.isEmpty()) {
            List<Predicate> predicates = new ArrayList<Predicate>();
            for(Criterion c : criterions){
                predicates.add(c.toPredicate(root, query,builder));
            }
            // 将所有条件用 and 联合起来
            if (predicates.size() > 0) {
                return builder.and(predicates.toArray(new Predicate[predicates.size()]));
            }
        }
        return builder.conjunction();
    }
    /**
     * 增加简单条件表达式
     * @Methods Name add
     * @Create In 2012-2-8 By lee
     * @param expression0 void
     */
    public void add(Criterion criterion){
        if(criterion!=null){
            criterions.add(criterion);
        }
    }
}  

然后是各种条件组装类，我首先做了一个接口来包装各种条件

1. /**
    * 条件接口
    * 用户提供条件表达式接口
    * @Class Name Criterion
    * @Author lee
    * @Create In 2012-2-8
    */
   public interface Criterion {
       public enum Operator {
           EQ, NE, LIKE, GT, LT, GTE, LTE, AND, OR
       }
       public Predicate toPredicate(Root<?> root, CriteriaQuery<?> query,
               CriteriaBuilder builder);
   }  

然后是针对不同类型条件处理的实现

一个是简单比较类型的处理

/**
 * 简单条件表达式
 * @author lee
 *
 */
public class SimpleExpression implements Criterion{  
 
    private String fieldName;       //属性名
    private Object value;           //对应值
    private Operator operator;      //计算符  
 
    protected SimpleExpression(String fieldName, Object value, Operator operator) {
        this.fieldName = fieldName;
        this.value = value;
        this.operator = operator;
    }  
 
    public String getFieldName() {
        return fieldName;
    }
    public Object getValue() {
        return value;
    }
    public Operator getOperator() {
        return operator;
    }
    @SuppressWarnings({ "rawtypes", "unchecked" })
    public Predicate toPredicate(Root<?> root, CriteriaQuery<?> query,
            CriteriaBuilder builder) {
        Path expression = null;
        if(fieldName.contains(".")){
            String[] names = StringUtils.split(fieldName, ".");
            expression = root.get(names[0]);
            for (int i = 1; i < names.length; i++) {
                expression = expression.get(names[i]);
            }
        }else{
            expression = root.get(fieldName);
        }  
 
        switch (operator) {
        case EQ:
            return builder.equal(expression, value);
        case NE:
            return builder.notEqual(expression, value);
        case LIKE:
            return builder.like((Expression<String>) expression, "%" + value + "%");
        case LT:
            return builder.lessThan(expression, (Comparable) value);
        case GT:
            return builder.greaterThan(expression, (Comparable) value);
        case LTE:
            return builder.lessThanOrEqualTo(expression, (Comparable) value);
        case GTE:
            return builder.greaterThanOrEqualTo(expression, (Comparable) value);
        default:
            return null;
        }
    }  
 
}  

一个逻辑条件计算实现

/**
 * 逻辑条件表达式 用于复杂条件时使用，如但属性多对应值的OR查询等
 * @author lee
 *
 */
public class LogicalExpression implements Criterion {
    private Criterion[] criterion;  // 逻辑表达式中包含的表达式
    private Operator operator;      //计算符  
 
    public LogicalExpression(Criterion[] criterions, Operator operator) {
        this.criterion = criterions;
        this.operator = operator;
    }  
 
    public Predicate toPredicate(Root<?> root, CriteriaQuery<?> query,
            CriteriaBuilder builder) {
        List<Predicate> predicates = new ArrayList<Predicate>();
        for(int i=0;i<this.criterion.length;i++){
            predicates.add(this.criterion[i].toPredicate(root, query, builder));
        }
        switch (operator) {
        case OR:
            return builder.or(predicates.toArray(new Predicate[predicates.size()]));
        default:
            return null;
        }
    }  
 
}  

添加一个组装工厂类

/**
 * 条件构造器
 * 用于创建条件表达式
 * @Class Name Restrictions
 * @Author lee
 */
public class Restrictions {  
 
    /**
     * 等于
     * @param fieldName
     * @param value
     * @param ignoreNull
     * @return
     */
    public static SimpleExpression eq(String fieldName, Object value, boolean ignoreNull) {
        if(StringUtils.isEmpty(value))return null;
        return new SimpleExpression (fieldName, value, Operator.EQ);
    }  
 
    /**
     * 不等于
     * @param fieldName
     * @param value
     * @param ignoreNull
     * @return
     */
    public static SimpleExpression ne(String fieldName, Object value, boolean ignoreNull) {
        if(StringUtils.isEmpty(value))return null;
        return new SimpleExpression (fieldName, value, Operator.NE);
    }  
 
    /**
     * 模糊匹配
     * @param fieldName
     * @param value
     * @param ignoreNull
     * @return
     */
    public static SimpleExpression like(String fieldName, String value, boolean ignoreNull) {
        if(StringUtils.isEmpty(value))return null;
        return new SimpleExpression (fieldName, value, Operator.LIKE);
    }  
 
    /**
     *
     * @param fieldName
     * @param value
     * @param matchMode
     * @param ignoreNull
     * @return
     */
    public static SimpleExpression like(String fieldName, String value,
            MatchMode matchMode, boolean ignoreNull) {
        if(StringUtils.isEmpty(value))return null;
        return null;
    }  
 
    /**
     * 大于
     * @param fieldName
     * @param value
     * @param ignoreNull
     * @return
     */
    public static SimpleExpression gt(String fieldName, Object value, boolean ignoreNull) {
        if(StringUtils.isEmpty(value))return null;
        return new SimpleExpression (fieldName, value, Operator.GT);
    }  
 
    /**
     * 小于
     * @param fieldName
     * @param value
     * @param ignoreNull
     * @return
     */
    public static SimpleExpression lt(String fieldName, Object value, boolean ignoreNull) {
        if(StringUtils.isEmpty(value))return null;
        return new SimpleExpression (fieldName, value, Operator.LT);
    }  
 
    /**
     * 大于等于
     * @param fieldName
     * @param value
     * @param ignoreNull
     * @return
     */
    public static SimpleExpression lte(String fieldName, Object value, boolean ignoreNull) {
        if(StringUtils.isEmpty(value))return null;
        return new SimpleExpression (fieldName, value, Operator.GTE);
    }  
 
    /**
     * 小于等于
     * @param fieldName
     * @param value
     * @param ignoreNull
     * @return
     */
    public static SimpleExpression gte(String fieldName, Object value, boolean ignoreNull) {
        if(StringUtils.isEmpty(value))return null;
        return new SimpleExpression (fieldName, value, Operator.LTE);
    }  
 
    /**
     * 并且
     * @param criterions
     * @return
     */
    public static LogicalExpression and(Criterion... criterions){
        return new LogicalExpression(criterions, Operator.AND);
    }
    /**
     * 或者
     * @param criterions
     * @return
     */
    public static LogicalExpression or(Criterion... criterions){
        return new LogicalExpression(criterions, Operator.OR);
    }
    /**
     * 包含于
     * @param fieldName
     * @param value
     * @return
     */
    @SuppressWarnings("rawtypes")
    public static LogicalExpression in(String fieldName, Collection value, boolean ignoreNull) {
        if(ignoreNull&&(value==null||value.isEmpty())){
            return null;
        }
        SimpleExpression[] ses = new SimpleExpression[value.size()];
        int i=0;
        for(Object obj : value){
            ses[i]=new SimpleExpression(fieldName,obj,Operator.EQ);
            i++;
        }
        return new LogicalExpression(ses,Operator.OR);
    }
}  

使用方法如下

Criteria<Event> c = new Criteria<Event>();
c.add(Restrictions.like("code", searchParam.getCode(), true));
        c.add(Restrictions.eq("level", searchParam.getLevel(), false));
        c.add(Restrictions.eq("mainStatus", searchParam.getMainStatus(), true));
        c.add(Restrictions.eq("flowStatus", searchParam.getFlowStatus(), true));
        c.add(Restrictions.eq("createUser.userName", searchParam.getCreateUser(), true));
        c.add(Restrictions.lte("submitTime", searchParam.getStartSubmitTime(), true));
        c.add(Restrictions.gte("submitTime", searchParam.getEndSubmitTime(), true));
        c.add(Restrictions.eq("needFollow", searchParam.getIsfollow(), true));
        c.add(Restrictions.ne("flowStatus", CaseConstants.CASE_STATUS_DRAFT, true));
        c.add(Restrictions.in("solveTeam.code",teamCodes, true));
eventDao.findAll(c);